For starters, the pressure switch will not shut down your pump should the well draw-down exceed your well depth. That is not what it is designed to do. Hence the name "pressure switch." It will shut the pump off when a certain pressure has been pumped into a tank. If there is no water coming into the pump there is no pressure building up and you run the very serious risk of running your pump dry for an extended period of time resulting in damage to the pump.
The pressure tank will activate the switch if properly adjusted according to the capacity of your pump. This will prevent damage should you close the water flow, ie stop using the water hose. As for shutting the pump down if the water level draw-down exceeds the depth of your well, I have no easy answer for you.